According to Reuters sources, the State Council has gathered evidence on the two firms for more than a month.
It plans to investigate whether the payments giants have used their dominant market position to prevent competition from gaining a significant foothold in China.
Both Alipay, owned by Ant Group and Alibaba, and Tencent Holding’s WeChat Pay are lobbying government officials to prevent the probe.
The investigation would be ill-timed for Ant Group, as it pursues a dual listing in Hong Kong and Shanghai. The firm is seeking a $200 billion valuation.